Add WCS GetCapabilities parsing for WCS 1.0.0 and 1.1.0

This pull request adds support for parsing WCS GetCapabiliites for WCS 1.0.0 and 1.1.0.  While I realize that working with WCS data on web based application is a fool's errand, getting information about the services and available data can be quite useful.

This code includes unit tests for all added functionality; all relevant tests are passing.

One other small change included here is that I moved the errorPorperty from the base class (WCSCapabilities) down to the parsers; this was a necessary change because there are no properties in common between WCS 1.0.0 and 1.1.0.  In any case, this change seems logical, as the parsers have more information about what constitutes successful parsing than do the base classes.  For consistency, I also altered the WFSCapabilities class to conform to this change.  I could not find any other classes that use errorProperty.  I had earlier discussed this change with Bart, and my solution is slightly different than what he suggested.  I think this code is cleaner and clearer, but I am open to differing opinions.